Electrically-heated hot-plate.



. F. KUHN.

ELECTRIGALLY HEATED HOT PLATE.

APPLICATION FILED SEPT. s, 1013.

1,107,321, Patented Aug.18,191

2 SHEETS-SHEET 1.

KUHN.

ELEGTRIOALLY HEATED HOT PLATE.

APPLICATION FILED SEPT. 8, 1913 1,107,321, Patented Aug. 18, 191 g l) v a 15 A $\\\\\\\\Q\\\\\\X\\\\Y\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\"I: ,1 f C if 7 Q N\ I R Z,\ M 0 Q I J 7 J,

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wxaw y UNITED STATES PA NT OFFICE. I

' FRANK KUI-Ill', 0F DETROIT, MICHIGAN.

ELECTRICALLY-HEATED HOT-PLATE,

Specification of Letters Patent.

Patented Aug. 18, 1914.

Application filed September a, 1913. Serial No. 788,715.

heating unit is arranged adjacent to a, fiat heat-distributing body mounted upon assupporting stand. 2 I

The invention comprises various :features of construction, by whichthe manufacture is simplified and cheapened and im roved results are obtained in operation, as herein: after set forth.

In the drawings: Figure 1 is a perspective view of the several sections inclosing the. heaterdetached; Fig. 2 is a verticalcross section through the assembled structure;

Fig. 3 is a detail sectional view showing the manner of'attaching the legs to the stand.

To increase the efficiency of the hot plate .and also to reduce the downward radiation of heat to the minimum, it is desirable to interpose a dead-air space between the heating unit and the supportingstand. This decreases the loss of heat by reason ofthe poor heat-conducting property of a static gas but to form such a. dead-air space there mustbe continuous retaining walls which will conduct down a certain amount of heat tothe supporting stand. With my .improved construction I form the dead-air space by a hollow member, preferably formed of cast metal having an annular wall marginally bearing against the hot plate. the downward radiation of heat conducted through this wall, I have provided thef'bottom of the hollow member with downwardly-projecting lugs, preferably integral therewith. These lugs are supported upon a stand forming a battle or radiation shield, and the space between the hollow member and thestand is surrounded by a perforated case, producing a finished appearance to the structure, and at the same time permitting of a free'air circulation, so that the downwardly conducted heat is dissipated by convection.

In detail, A is the hot plate, tothe' lower with a clamping and heat-distributing plate To prevent' .(J therebeneath, threaded studs D and nuts E be ng preferably the clamping means. I

F is the hollow member, preferably a casting, and havingan annular outer wall upon which the margin of the hot plate is seated.

This member-is also provided with integral lugs G depending therefrom and its bottom plate H is cut away at H for the terminal connection, as hereinafter described.

I is a fiat plate or shield, which forms the top of the stand, having depending legs J secured thereto. These legs are arranged opposite the lugs G on the member F and are secured to said lugs by suitable means, .such as screws.

The plate I is preferably formed of sheet metal, while the legs may be formed of castings, thereby simplifying and cheapening the construction. On the bottom of the plate I is, secured 'a terminal contact box K, from which conductors lead through insulator-bushings L placed in aper- 'tures in the plate I. There is also a SWltClL M mounted beneath the plate I so as to be operable from, the front of the stand, and the insulator block M, upon which this switch is mounted, extends through an aperture in the plate I andabove the same a sufiicient distance to hold the conductors out 0fcontact with the metal parts. The conductors N from the terminals pass from the bushings L to the block M where they are coupled to the switch, while a plurality of conductorsv 0 lead from the switch to the hot plate. These conductors 0 pass through the space between the member F and the plate I,

and are secured to an insulator block P, which: latter is clamped to'the hot plate and projects downward through the cutaway portion H into the space in which the conductors O are located. Extension conductors Q, formed of strips of sheet metal are electrically connected to the conductors O and are clamped to the block P by screws Q.

These extension conductors are bent at right angles and extend in to the rooves in the block P to points in proximity to the hot plate, so that the resistor wire may be connected thereto without exposing any considerable length to the air, and thereby preventingoverheating or burning out of the resistor at this point.

\ all of the member l1. This will permit the tree circulation of air between the member l and the plate I, but at the same time the naked conductor wires are inclosed so as to prevent any danger of shortficircuit.

All of the parts are secured together by the studs D, some of which pass through the bottom plate I and are clamped" thereto by nuts l3.

What I claim as my invention is: i p

1. An electric heater, comprising a hot plate, an electrical heating element clamped to the underside of said plate, an insulator block secured to said hot plate and depend ing therefrom, terminal connections for the resistor mounted on said insulator block, a hollow member having an annular outer wall forming a seat for said hot plate and a bottom cut away at one point for the passage of said insulator block, supporting lugs depending from said hollow member, a stand comprising legs and a top plate on which latter the lugs of said hollow member are supported, terminal contacts and a controlling switch mounted on said stand beneath the same,'and electrical connections between said terminal contacts and switch and between the latter andthe terminals on said insulator block, being detachably secured to the latter.

2. An electric heater,-comprising a hotplatc, an electrical heating unit clamped to the underside of said plate, a stand forsupporting said plate, having terminal connections mounted thereon, a hollow cast member interposed between said hot plate and stand, comprising an annular wall, a botrot/ear tom and depending lugs, said lugs being supported on said stand, and a perforated annular casing surrounding said lugs inclosing the space between said hollow memher and stand.

3. An electric heater, comprising a, hot plate, an electrical heating unit clamped to the underside thereof, a stand having a top plate and depending legs, electrical connections mounted upon said stand, and a hollow member interposed between said stand and said hot plate formed'of cast metal having anannular wall forming a seat for the hot plate, a bottom plate and'depending lugs, the latter registering with the legs of said stand and being secured thereto.

at. lln'electric heater, comprising a hot plate, an electrical heatingunit clamped to the underside of said plate, a stand comprising-a topplate and depending legs, electrical terminal connections mounted on said stand on the underside thereof and provided with upwardly-extending insulators passing through apertures insaid top plate, ahollow member'interposed between said stand and hotvplate comprising an annular wall't orming a seat for the hot plate, a bottom and depending lugs, an insulator block on said hot plate depending thereifroin and passing through an aperture in the bottom of said hollow member, terminal connections for the heating unit mounted on said insular block, naked conductors for connecting said terminal connections on said block with the terminals mounted on said stand, and a perforated shield surrounding the space between said stand and hollow member in which said naked conductors are located and permitting the tree circulation of air.

In testimony whereof I aiiix my signature in presence oftwo witnesses."

l ltANK K UHN. li itnesses lVM. J. BELKNAP, JAMES :3. Benny. 

